JP3278349B2 - Sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device such as an oil seal used for a shaft sealing portion of various devices, and more particularly to a structure having a screw portion on a sliding surface on the atmosphere side.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional sealing device of this type. That is, the sealing device 100 seals an annular gap between a housing 101 as two members that are concentrically and relatively rotatably assembled with each other and a rotating shaft 102 inserted into the housing 101.

The sealing device 100 includes a housing 101
And a seal lip 104 made of, for example, a rubber-like elastic body, which slidably and sealingly contacts the outer peripheral surface of the rotating shaft 102. Further, a spring 106 for applying a tightening force is mounted on the outer periphery of the seal lip 104.

A screw protrusion 105 is formed as a screw portion on the sliding surface of the seal lip 104 on the atmosphere side, and the sealing performance is enhanced by the pumping action of the screw protrusion 105 (screw effect).

The shape of the screw protrusion 105 is a parallel screw protrusion 105A (see FIG. 7 (a)) having a substantially constant height and width. Both ends in the axial direction are closed. there is great Funesoko threaded projection 105B (see FIG. 7 (b)).

[0006]

However, since the height and width of the parallel screw protrusion 105A are substantially constant,
Although the initial sealing property is ensured, if the seal lip 104 wears over time, the screw effect is reduced.

Generally, the production of the sealing device 100 is performed by vulcanizing and molding a rubber material in a cavity formed by a mold. At this time, burr 104A is formed on the seal lip 104 parts as shown in FIG. 8,
By Mesukatto at the position (see arrow B portion) shown in FIG. 8, the seal lip 10 having a desired thread protrusion 105
I got 4. For straight thread protrusions 105A in FIG. 8 (a), shows a case of Funesoko screw projections 105B in Figure 8 (b).

[0008] The screw protrusion 105 is machined by a screw portion provided on the mold. This thread protrusion processing range 10
In the case of the parallel screw projection 105A, 7 is widened including the variation in the position of the knife cut (dotted line in the figure). This makes it possible to absorb a slight variation in the position of the knife cut. This is because the shape of the parallel screw protrusion 105A is
This is because the height and the width are almost constant.

However, the shape of the boat bottom screw protrusion 105B is not uniform in height and width as in the parallel screw protrusion 105A, and both ends in the axial direction are closed, and the height and width become larger toward the middle part in the axial direction. Therefore, it is effective against wear, but has the following problem due to manufacturing variations.

That is, when the position of the knife cut is shifted toward the burr 104A or the position of the bottom screw protrusion 105B is shifted toward the atmosphere A, the closed axial end of the bottom screw protrusion 105B is sealed. In some cases, the lip tip of the lip 104 may not be reached, and there may be no initial screw effect.

When the position of the knife cut is shifted to the atmosphere side A, or the position of the bottom screw protrusion 105B is
When it shifts to the A side, a portion where the height and width of the boat bottom screw protrusion 105B are large may be opened to the sealed fluid side O, and there is a fear of gap leakage.

From the above, in the case of the boat bottom screw protrusion 105B, the processing range of the screw protrusion of the mold is limited.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to prevent a decrease in sealability due to abrasion of a seal lip, and to provide both initial and durable performance. An object of the present invention is to provide a sealing device capable of maintaining a screw effect.

Another object of the present invention is to prevent the initial sealing performance from being deteriorated due to manufacturing variations.

[0015]

In order to achieve the above object, according to the present invention, an annular gap between two members which are concentrically and rotatably assembled with each other is sealed, and the two members are sealed. An annular seal main body attached to one of the members, and a seal lip slidably sealingly contacting the other of the two members provided on the seal main body. In a sealing device provided with a screw portion on a sliding surface, the shape of the screw portion is such that a sub-thread portion having a substantially uniform height and a uniform shape is continuously provided at a lip tip side of the main screw portion, and the main screw portion is provided . Part is air from the sub-thread part
Grows toward the side and
It is characterized in that the contact width is increased .

Preferably, the shape of the screw portion is a protrusion, and at least one of the height and the width is increased from the tip of the lip toward the atmosphere.

Further, the shape of the screw projection is substantially constant at a height and width smaller than the middle portion of the bottom screw projection on the lip tip side of the bottom screw projection whose height and width are larger in the middle part in the axial direction. It is preferable that the parallel thread projections are provided continuously.

Further, it is preferable that, in the bottom screw protrusion having a height and a width that is larger in a middle portion in the axial direction, the middle portion in the axial direction at the height is closer to the atmosphere side.

In the sealing device having the above-described structure, since the screw portion is provided on the sliding surface on the atmosphere side of the seal lip, a high sealing performance by a pumping action is obtained as a screw effect.

The shape of the screw portion is such that a sub screw portion having a substantially constant height and a uniform shape is continuously provided at the tip end side of the lip of the main screw portion, and the main screw portion moves from the sub screw portion to the atmosphere side. big
Since the contact width increases with use time (wear), the thread has a threaded portion even if the seal lip is worn, so that the screw effect can be maintained for the seal lip member. it can. As a result, it is possible to prevent a decrease in sealing performance due to abrasion, and it is possible to maintain high sealing performance by a screw effect both initially and durably.

[0021] Further, the shape of the screw portion is a projection, and at least the height and width of the protrusion are increased from the tip of the lip toward the atmosphere, so that even if the seal lip is worn, the screw is surely worn. With such a configuration, it is possible to maintain a good contact state having a screw effect on the member of the seal lip. As a result, it is possible to further prevent a decrease in sealing performance due to wear, and to maintain high sealing performance due to the screw effect both initially and durably.

Further, the shape of the screw protrusion is provided by providing a parallel screw protrusion having a substantially constant height and width on the tip end side of the lip of the boat bottom screw protrusion. When obtaining a desired seal lip having a screw protrusion by scalping the generated burrs, variation in the position of the scalpel cut can be absorbed by increasing the processing range of the parallel screw protrusion on the lip tip side of the mold.

As a result, the tip of the screw projection does not reach the tip of the lip or the screw projection does not open too much.
The gap leakage can be prevented.

If the sliding surface of the seal lip on the atmosphere side is an inclined surface, the midway portion in the axial direction where the height of the bottom screw projection is the highest is set closer to the atmosphere side. Even when the eccentricity is large, the squeezing amount of the bottom screw projection in the early stage of use can be reduced, so that the sealing fluid does not leak, and the sealing performance can be further improved.

In addition, the contact width of the screw projection with the shaft increases with use time (wear), so that the service life can be extended.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

(Embodiment 1) FIG. 1 shows a sealing device according to Embodiment 1 of the present invention.
A housing 2 as a two member which is concentrically and relatively rotatably assembled with each other, and a shaft 3 inserted into the housing 2
It seals the annular gap between them.

The sealing device 1 includes a seal body 4 fitted on the inner periphery of the housing 2, a seal lip 5 slidably sealingly contacting the outer peripheral surface of the shaft 3, and a shaft 3 of the seal lip 5. And a screw protrusion 6 as a screw portion formed on the atmosphere side sliding surface 51 with the outer peripheral surface.

The seal body 4 includes a reinforcing ring 7 and a rubber-like elastic body 8. The reinforcing ring 7 is a cylindrical member having an inward flange portion 71 extending inward in the radial direction. Atmospheric side A end face of the flange portion 71 of the reinforcing ring 7 and the cylindrical portion 7
A rubber-like elastic body 8 is integrally fixed to the outer peripheral surface 2 and the end surface O on the sealed fluid side by baking.

The seal body 4 is provided with a cylindrical portion 7 of a reinforcing ring 7.
2 is fitted to the inner peripheral surface of the housing 2 via a rubber-like elastic body 8.

The seal lip 5 and the dust lip 9 made of rubber-like elastic material are provided at the inner end of the flange portion 71 of the reinforcing ring 7.

The seal lip 5 has a wedge-shaped section extending from the inner end of the flange portion 71 to the rubber-like elastic body 8 and extending toward the sealing fluid side O in the axial direction, and the tip of the lip slides on the outer peripheral surface of the shaft 3. It is movably sealed.

On the outer periphery of the seal lip 5, a spring 10 as a tensioning means for applying a tensioning force to the outer peripheral surface of the shaft 3 is mounted all around.

The dust lip 9 extends in the axial direction A from the inner end of the flange portion 71 of the reinforcing ring 7 and inclines toward the shaft 3, and has a plate-like cross section. 3
Slidably and sealingly in contact with the outer peripheral surface of the rim.
This prevents dust from entering from the atmosphere side A.

The sliding surface 5 on the atmosphere side of the seal lip 5
1 is provided with a screw projection 6 to enhance the sealing performance by the pumping action (screw effect).

The screw protrusion 6 is a combination of a parallel screw protrusion 61 as a sub-screw portion and a boat bottom screw protrusion 62 as a main screw portion, and the lip tip side of the boat bottom screw protrusion 62 is parallel. This is a screw projection 61.

The height and width of the boat bottom screw protrusion 62 are increased toward the middle part in the axial direction. The details will be described below with reference to FIGS. 1 (b) and 1 (c).

The axial cross section (cross section taken along the line Y--Y in FIG. 1 (c)) has an arcuate shape, and is higher in the middle. In appearance, it has a substantially elliptical shape in which both ends in the axial direction are pointed, becomes wider toward the middle, and has a triangular cross section in the circumferential direction (cross section taken along line XX in FIG. 1B).

A parallel screw projection 61 is provided so as to be connected to the lip tip end of the boat bottom screw projection 62.
The parallel screw protrusion 61 has a triangular cross section, and the height and width are smaller than the middle part of the boat bottom screw protrusion 62 and are substantially constant.

The height and width of the so-called screw protrusion 6 are reduced toward the lip tip side of the seal lip 5 and are increased toward the atmosphere side A (up to a halfway portion of the boat bottom screw protrusion 62 in the axial direction).

In the sealing device having the above-described structure, the shape of the screw protrusion 6 provided on the atmosphere side sliding surface 51 of the seal lip 5 is changed to the parallel screw protrusion 6 with the lip tip side of the boat bottom screw protrusion 62.
As 1, the height and width are increased from the lip tip toward the atmosphere side A to the middle part in the axial direction of the boat bottom screw protrusion 62, so that the parallel screw protrusion 61 has an initial sealing property due to the screw effect. During the wear of the seal lip 5, a good contact state with the shaft 3 can be maintained satisfactorily with the boat bottom screw protrusion 62, and there is no decrease in the sealing performance due to the wear. As described above, the initial sealing performance by the parallel screw protrusions 61 can be ensured, and the sealing performance can be prevented from deteriorating due to abrasion. Can be achieved.

When a general sealing device is manufactured by vulcanizing a rubber material into a cavity formed by a molding die (not shown) having a thread projection, a seal lip 5 parts is formed. Is formed, and a desired seal lip 5 having a screw projection 6 is obtained by scalpel cutting the burr. At this time, since the tip side of the lip to be knife-cut is the parallel screw projection 61, the screw screw processing range of the parallel screw projection 61 can be widened to absorb variations in the position of the knife cut. This facilitates the molding.

Table 1 shows the contact state of the seal lip of the screw projection with the parallel screw projection + boat bottom screw projection according to the present embodiment and the parallel screw projection, which is a conventional parallel screw portion, with the passage of time. Show.

[0044]

[Table 1] As shown in Table 1, in the case of the conventional parallel screw protrusion having only a substantially constant height and width, the screw protrusion portion disappears as the seal lip wears. Therefore, as the seal lip wears, the screw effect decreases.

On the other hand, in the case of the screw projection according to the present embodiment, even if the seal lip wears out and the parallel screw projection disappears, the boat bottom with the increased height and width is provided on the atmosphere side. Since the screw projection is provided, even if the seal lip is worn, the seal lip has the screw projection portion, and the seal lip maintains a good contact state with the screw projection on the shaft. Therefore, it has a screw effect even after the seal lip is worn.

Next, FIG. 2 shows the relationship between the amount of leakage (on the side of the sealed fluid) of the parallel screw protrusion + boat bottom screw protrusion according to the present embodiment and the conventional parallel screw protrusion, and the test time. Show.

In FIG. 2, the solid line is only the conventional parallel screw projection, and the dashed line is the parallel screw projection + boat bottom screw projection according to the present embodiment.

With the conventional parallel screw projection alone, the amount of leakage from the back surface is initially large, but the amount of leakage decreases rapidly as the wear of the seal lip progresses over time. In other words, this indicates that the screw effect is reduced due to the wear of the seal lip, and the sealing performance is reduced.

In the case of the parallel screw protrusion and the boat bottom screw protrusion according to this embodiment, the amount of leakage from the back surface is large at the initial stage due to the parallel screw protrusion, and the height and width are increased even if the seal lip is worn over time. Less reduction due to larger than parallel thread projection. That is, there is no reduction in the sealing performance due to the wear of the seal lip.

It is to be noted that the dotted line in the figure shows the case where only the conventional boat bottom screw projection is provided, and the tip of the boat bottom screw projection does not reach the tip of the lip. That is, since the tip of the screw projection has not reached, the screw effect cannot be obtained at the initial stage, and the amount of back surface leakage is extremely small. Therefore, it does not initially have high sealing performance.

Incidentally, in the boat bottom screw projection 62 in which the height and the width of the screw projection 6 according to the first embodiment become larger in the middle part in the axial direction, the center part in the axial direction is the highest. The air-side sliding surface 51 of the seal lip 5 provided with the boat bottom screw protrusion 62 is an inclined surface.

From these, when the eccentricity of the shaft 3 is large, the contact state of the seal lip 5 and the screw protrusion 6 with the shaft 3 in the initial stage of use is as shown in FIG.
There is a problem that the crushing amount (h ′) of 2 becomes large, the tip of the lip rises, and the sealed fluid leaks.

The relationship between the contact width a of the seal lip 5 and the contact width a 'of the screw projection 6 with the shaft 3 which determines the amount of the pump that forms a screw effect for improving the sealing performance is as follows. Has become.

That is, as shown by the solid line in FIG. 5A showing the contact state and the solid line in FIG.
After passing through the central portion in the axial direction, the temperature drops rapidly, which hinders a long life.

(Embodiment 2) Therefore, the screw protrusion 6
In order to solve the drawback, the screw projection 6A shown in FIG. 3 is used.
This will be described below as a second embodiment of the present invention.
The same components as those in the first embodiment are denoted by the same reference numerals in the drawings, and the description of the configuration and operation will be omitted.

The screw projection 6A according to the second embodiment is
In the bottom screw projection 62A according to the first embodiment, the highest point of the bottom screw projection 62A is closer to the atmosphere side A than the center in the axial direction, and the highest (hmax in the figure).
However, the air side A is notched, and a notch 62B is provided.

In order to make the highest portion of the bottom screw protrusion 62A closer to the atmosphere side A, the radius R of the circular arc forming the bottom of the boat may be increased as compared with the first embodiment.

In the figure, h indicates the height of the parallel screw projection 61, and H indicates the length of the parallel screw projection 61.

FIG. 4B shows a state of contact of the screw projection 6A with the shaft 3 at the initial stage of use. As shown in the figure,
Since the highest portion of the bottom screw projection 62A is closer to the atmosphere side A, even when the eccentricity of the shaft 3 is large, the crush amount (h ') of the bottom screw projection 62A is smaller than that in the first embodiment. Therefore, the sealed fluid does not leak. That is, the sealing property is improved.

The relationship between the contact width a of the seal lip 5 and the contact width a 'of the screw projection 6A is as shown by the dotted lines in FIG. 5B and FIG.

That is, since the highest portion of the bottom screw protrusion 62A is closer to the atmosphere side A, the dimension of the contact width a 'of the screw protrusion 6A increases with time (wear). In particular, when the contact width a of the seal lip 5 is large, the contact width a 'of the screw protrusion 6A is large, and the life is longer than that of the screw protrusion 6 of the first embodiment.

[0062]

[0063]

[0064]

In each of the above embodiments, the shape of the screw protrusion as the screw portion is described as an example in which the height and width are increased toward the atmosphere side. However, the screw effect on the wear of the seal lip is slightly increased. Although it may be smaller, if the height is increased, the screw protrusion can be provided even if worn, so that it is sufficient if the height is increased at least.

Further, in this embodiment, the seal lip is described as a rubber-like elastic body, but may be made of resin.

[0067]

The present invention has the above-mentioned structure and operation. The shape of the screw portion is such that a sub-thread portion having a substantially constant height and a uniform shape is continuously formed at the lip tip side of the main screw portion. Provided ,
The main thread increases from the sub-thread toward the atmosphere,
Since the contact width increases with use time (wear) , even if the seal lip is worn, it has a threaded portion, and the screw effect can be maintained on the member of the seal lip. As a result, it is possible to prevent a decrease in sealing performance due to abrasion, and it is possible to maintain high sealing performance by a screw effect both initially and durably.

Also, since the shape of the screw portion is a protrusion, and at least the height and width of the protrusion are increased from the tip of the lip toward the atmosphere, even if the seal lip is worn, it is ensured. Since it has a screw portion, it is possible to maintain a favorable contact state having a screw effect on the member of the seal lip. As a result, it is possible to further prevent a decrease in sealing performance due to wear, and to achieve a high sealing performance by a screw effect both initially and durably. Therefore, the sealing performance can be further improved.

Further, if the width is increased toward the atmosphere side, a better contact state having a thread portion can be maintained during the progress of the wear of the seal lip.

The shape of the screw projection is such that a parallel screw projection having a substantially constant height and width is provided on the tip end side of the lip of the boat bottom screw projection. When a desired seal lip having a screw protrusion is obtained by scalping the generated burrs, the processing range of the parallel screw protrusion on the lip tip side of the mold can be widened, and variation in the position of the scalpel cut can be absorbed.

As a result, the tip of the screw projection does not reach the tip of the lip, and the screw projection does not open too much.
The gap leakage can be prevented. Therefore, it is possible to prevent the initial sealing performance from being lowered due to manufacturing variations.

When the sliding surface on the atmosphere side of the seal lip is an inclined surface, the midway portion in the axial direction where the height of the bottom screw projection is the highest is set closer to the atmosphere side. Even when the eccentricity is large, the squeezing amount of the bottom screw projection in the initial stage of use can be reduced, so that the sealing fluid does not leak and the sealing performance can be further improved.

In addition, the contact width of the screw projection with the shaft increases with the use time (wear), so that the life can be extended.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a sealing device according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view taken along line XX of FIG.
FIG. 3C is a sectional view taken along a line, and FIG. 3C is a sectional view taken along the line YY of FIG.

FIG. 2 is a diagram showing a relationship between a back surface leakage amount and a test time.

FIG. 3 is a sectional view of a main part of a sealing device according to a second embodiment of the present invention.

FIGS. 4A and 4B are schematic diagrams showing the state of contact between the shaft eccentricity and the seal lip. FIG. 4A shows the first embodiment, and FIG. 4B shows the second embodiment.

5A and 5B are diagrams showing contact widths of a shaft, a seal lip, and a screw protrusion. FIG. 5A shows the first embodiment, and FIG. 5B shows the second embodiment.

FIG. 6 is a diagram showing a relationship between a lip contact width and a screw contact width.

FIG . 7 is a sectional view of a conventional sealing device,
(A) shows the shape of the screw protrusion as a parallel screw protrusion.
(B) is a bottom screw protrusion.

FIG. 8 shows a scalpel cutting process of a conventional sealing device.
FIG. 4A is a cross-sectional view of a main part, in which FIG.
The case of a screw protrusion is shown, and FIG.
It shows the case of the origin.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing device 2 Housing 3 Shaft 4 Seal body 5 Seal lip 51 Atmospheric side sliding surface 6, 6A Screw protrusion (screw part) 6 'Screw groove (screw part) 61 Parallel screw protrusion 61' Parallel screw groove 62, 62A Ship bottom Screw protrusion 62B Notch portion 62 'Boat bottom screw groove 7 Reinforcement ring 71 Flange portion 72 Cylindrical portion 8 Rubber elastic body 9 Dustrip 10 Spring

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-226547 (JP, A) JP-A-8-291867 (JP, A) JP-A-8-178082 (JP, A) 19811 (JP, B1) Jikken 46-9620 (JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16J 15/32 311

Claims (4)

(57) [Claims] An annular seal body attached to one of the two members which is concentrically and relatively rotatably assembled with each other, and provided on the seal body. A sealing lip slidably and sealingly contacting the other of the two members, wherein a screw portion is provided on the air-side sliding surface of the seal lip. continuously providing the auxiliary threads of uniform shape height to the lip distal side of the main threaded portion is substantially constant, the main
The thread increases from the sub-thread toward the atmosphere.
And a contact width increases with use time (wear) . 2. The sealing device according to claim 1, wherein a shape of the screw portion is a protrusion, and at least one of height and width is increased from a lip tip toward the atmosphere. 3. The shape of the screw protrusion is substantially constant at a height and width smaller than the middle portion of the ship bottom screw protrusion on the lip tip side of the ship bottom screw protrusion whose height and width are larger in the axial middle portion. 3. The sealing device according to claim 2, wherein the parallel screw projections are continuously provided. 4. The sealing device according to claim 3, wherein in the bottom screw protrusion having a height and a width which is larger in a middle portion in the axial direction, the middle portion in the axial direction at the height is closer to the atmosphere side. .